Doxofylline exerts a prophylactic effect against bronchoconstriction and pleurisy induced by PAF.

The effect of doxofylline, a new xanthine drug with a low incidence of side-effects in the central nervous, renal and gastroenteric system, on the actions of PAF-acether on bronchopulmonary functions was studied. Doxofylline inhibited: (1) PAF-induced bronchoconstriction in vitro, and the concomitant generation of TXA2-like activity in perfused guinea-pig lungs; (2) PAF-induced bronchoconstriction in vivo and the concomitant release of TXA2-like activity into the circulation; (3) PAF-acether-induced pleurisy and the liberation of type C4 leukotriene into the rat pleural cavity. The results suggest that doxofylline, like theophylline, is able to counteract the bronchoconstriction induced by PAF-acether and, in addition, displays anti-inflammatory properties. These pharmacological data support the notion that doxofylline exerts a prophylactic effect against the respiratory damage induced by mediators, such as PAF-acether, of lung bronchial hyperreactivity; its mechanism of action is unusual, it has slight antagonistic activity at A1- and A2-adenosine receptors.